The current study investigates the fitness cost associated with phosphine resistance in the rusty grain beetle, Cryptolestes ferrugineus (Stephens), a problematic pest in the stored commodities that has developed strong resistance to fumigant phosphine. Three characterised insect strains: the susceptible (Ref-S), the strongly resistant (Ref-R), the introgressed resistant (Intro-R) and a segregating population (F₂₅) derived from crossing the Ref-S and Ref-R strains were used in this study. Intro-R was developed by introgressing two phosphine resistance genes, cf_rph1 and cf_rph2 into Ref-S, aimed to reduce the influence of background genetic factors. Intro-R exhibited 592 × resistance to phosphine and homozygous for strong resistance allele, cf_rph2 (L73N). Two key fitness cost criteria, developmental time and fecundity, were assessed under optimal and suboptimal conditions (less favourable diet and low temperature). There was no significant difference in developmental time and fecundity between Ref-S and either Intro-R strain or F₂₅ under optimal conditions. When challenged with a less favourable diet, cracked wheat + cracked sorghum (CW + CS), or exposed to a low temperature (22 °C), both Intro-R and Ref-S had similar developmental time and total numbers of F₁ progeny, confirming the absence of significant fitness effects expressed in these conditions. Therefore, we conclude that strongly phosphine resistant C. ferrugineus are unlikely to incur potential fitness costs. This finding will have implications towards developing strategies to manage this pest.

当前的研究调查了与生锈的甲虫Cryptolestes ferrugineus（Stephens）的磷化氢抗性有关的适应性成本。三种特征性昆虫菌株：易感性（Ref-S），强抗性（Ref-R），渗入抗性（Intro-R）和种群隔离（F ₂₅在研究中使用了从Ref-S和Ref-R菌株杂交获得的）。Intro-R是通过将两个膦抗性基因cf_rph1和cf_rph2渗入Ref-S而开发的，目的是减少背景遗传因素的影响。Intro-R对膦具有592×的抗性，而强抗性等位基因cf_rph2（L73N）则是纯合的。在最佳和次优条件（较差的饮食和低温）下评估了两个关键的健身成本标准，即发育时间和繁殖力。Ref-S与Intro-R菌株或F ₂₅之间的发育时间和繁殖力没有显着差异在最佳条件下。当受到不利的饮食，破裂的小麦+破裂的高粱（CW + CS）或暴露于低温（22°C）的挑战时，Intro-R和Ref-S的发育时间和F ₁后代总数相似，确认在这些情况下没有明显的健身效果。因此，我们得出结论，对膦具有强抗性的C. ferrugineus不太可能招致潜在的健身费用。这一发现将对制定控制这种有害生物的策略产生影响。